On Thu, 29 Mar 2007 17:21:26 +0530 "Amit K. Arora" <aarora@xxxxxxxxxxxxxxxxxx> wrote: > Hello, > > We need to come up with the best possible layout of arguments for the > fallocate() system call. Various architectures have different > requirements for how the arguments should look like. Since the mail > chain has become huge, here is the summary of various inputs received > so far. > > Platform: s390 > -------------- > s390 prefers following layout: > > int fallocate(int fd, loff_t offset, loff_t len, int mode) > > For details on why and how "int, int, loff_t, loff_t" is a problem on > s390, please see Heiko's mail on 16th March. Here is the link: > http://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg133595.html > > Platform: ppc, arm > ------------------ > ppc (32 bit) has a problem with "int, loff_t, loff_t, int" layout, > since this will result in a pad between fd and offset, making seven > arguments total - which is not supported by ppc32. It supports only > 6 arguments. Thus the desired layout by ppc32 is: > > int fallocate(int fd, int mode, loff_t offset, loff_t len) > > Even ARM prefers above kind of layout. For details please see the > definition of sys_arm_sync_file_range(). This is a clean-looking option. Can s390 be changed to support seven-arg syscalls? > Option of loff_t => high u32 + low u32 > -------------------------------------- > Matthew and Russell have suggested another option of breaking each > "loff_t" into two "u32"s. This will result in 6 arguments in total. > > Following think that this is a good alternative: > Matthew Wilcox, Russell King, Heiko Carstens > > Following do not like this idea: > Chris Wedgwood It's a bit weird-looking, but the six-32-bit-args approach is simple enought to understand and implement. Presumably the glibc wrapper would hide that detail from everyone. > > What are your thoughts on this ? What layout should we finalize on ? > Perhaps, since sync_file_range() system call has similar arguments, we > can take hint from the challenges faced on implementing it on various > architectures, and decide. > - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
